The present invention relates to the genes causative of rheumatoid arthritis, a method for diagnosing rheumatoid arthritis using the mutations of these genes as the indicators, and a method for identifying the causative factors of rheumatoid arthritis.
The aspects of arthritis and joint damage causing rheumatoid arthritis, particularly the pathological courses thereof, have been elucidated gradually through various research works. Because many of the autoimmune diseases including rheumatoid arthritis are induced by the concomitant participation of numerous causative factors and are then exacerbated progressively to the stage of apparent diseases, however, the interactive mechanism per se of such numerous factors should be elucidated for accurate characterization and appropriate therapeutic management of the disease.
The prevalent rheumatoid arthritis is about 1% (N. Engl. J. Med., 322: 1277-1289, 1990), but the frequency of the disease is about 8 times increased in the siblings of the patients with the disease (Cell, 85: 311-318, 1996). Hence, it is predicted that a certain genetic factor may serve as one of the causative factors. Nevertheless, molecular genetic technology and genetic engineering technology for general use for identifying of genetic factors of diseases never function effectively in case of autoimmune diseases, because the onset of autoimmune diseases is never induced via such a biologically simple mechanism as abnormal amplification of one mutated gene as in the case of cancer. Conventional strategies of traditional genetics for the elucidation of the fundamental genetic pathogenesis of diseases have demonstrated distinctively that autoimmune diseases are caused by genetic multi-factor inheritance, but the strategies were apparently insufficient. As has been described above, none of the genes involved in rheumatoid arthritis or none of the loci of the genes on chromosome have absolutely been evidenced so far.
Alternatively, the linkage analysis method and the positional cloning method by means of polymorphic markers have opened an innovative progress recently in the field of research works on genetic diseases. By using these methods, not only the chromosomal locations of disease genes previously never characterized have been identified but also the causative genes of numerous diseases have been isolated and assayed (Experimental Medicine, Vol. 12, No. 6: 80-85, 1994). More recently, the causative gene of type I diabetes mellitus has been isolated (Nature, 171: 130-136, 1994), owing to a sib-pair analysis method comprising usage of the linkage analysis using a microsatellite marker as the polymorphic marker (Nature, 359: 794-801, 1992; Nature Genet., 7: 246-336) and the analysis of patient pedigrees as one of the procedures of traditional genetics. Thus, it becomes possible that genes causing diseases hardly curable because of the current absence of any effective therapeutic means, including autoimmune diseases, will be identified.
In such circumstances and the latest progress of the research works, the present application has been submitted. It is an object of the invention to provide the genes causative of rheumatoid arthritis, the chromosomal locations of these genes firstly being specified, a method for diagnosing rheumatoid arthritis using the mutations of these genes as the indicators, and a method for identifying the causative factors of rheumatoid arthritis.
In accordance with the application of the invention to overcome the aforementioned problems, the following individual genes are provided.
1. A gene causative of rheumatoid arthritis, which gene is located within xc2x11 centimorgan from a DNA sequence on human chromosome 1 to which the microsatellite markers D1S214 and/or D1S253 are hybridized.
2. A gene causative of rheumatoid arthritis, which gene is located within xc2x11 centimorgan from a DNA sequence on human chromosome 8 to which the microsatellite marker D8S556 is hybridized.
3. A gene causative of rheumatoid arthritis, which gene is located within xc2x11 centimorgan from a DNA sequence on human chromosome X to which the microsatellite markers DXS1001, DXS1047, DXS1205, DXS1227 and/or DXS1232 are hybridized.
In accordance with the application, a method for diagnosing rheumatoid arthritis, comprising amplifying the genomic DNA of a subject by PCR method using as primer at least one of microsatellite markers D1S214, D1S253, D8S556, DXS1001, DXS1047, DXS1205, DXS1227 and DXS1232, and then comparing the resulting PCR products with the PCR products prepared in the same manner using the genomic DNA of a normal control.
In accordance with the application, furthermore, a method for identifying the causative factors of rheumatoid arthritis, comprising amplifying the genomic DNA of a subject by PCR using as primer at least one of microsatellite markers D1S214, D1S253, D8S556, DXS1001, DXS1047, DXS1205, DXS1227 and DXS1232, and then comparing the resulting PCR products with the PCR products prepared in the same manner using the genomic DNA of a normal control.